In August 2014, CBS News published a story and a cellphone photo of a bizarre meteorological phenomenon. The reporter used a photo provided by a tugboat captain, who stated that he was not a meteorologist but described the image as a rare “sideways tornado.” The phenomenon is actually more than rare: it does not exist. The reporter could have consulted with the TV station's meteorologist, who later easily identified the photo as a shelf cloud. The story was pulled off their website and then amended, but the embarrassment for the news network did not go away.

Hoaxes in media are centuries old. Noted satirists such as Jonathan Swift in the seventeenth century and Mark Twain in the eighteenth were successful at spreading them well before the Internet (Walsh, 2006). Disaster-related media hoaxes predate the Internet by decades. A famous example was the 1938 radio adaptation of the alien-invasion novel byH.G.Wells, TheWar ofWorlds,which at the time caused numerous calls to newspapers and the police, and created a significant media backslash for (unintentionally, according to its producers) “deceiving” the listeners. Social media simply places the tools necessary to create and spread all kinds of information, including hoaxes, on the hands of many.

This chapter deals with concerns about the presence of false information in social media, which are frequently cited as one of the major obstacles to its adoption by humanitarian and emergency relief organizations (Hiltz et al., 2011; Hughes et al., 2014b). Officers at these organizations have said that they often find themselves wondering if they can trust a given piece of information from social media, or not. Some of them believe that social media are more likely than other sources to contain bad, false, unverified, or inaccurate information (Bressler et al., 2012; Vieweg et al., 2014). Emergency managers, who may also want to integrate information provided by the community, have also expressed doubts about the accuracy and reliability of social media (Merrick and Duffy, 2013). While disaster response organizations are used to operate with “good enough” information during emergencies, they seem to hold higher, even “unreasonable” standards of accuracy for data from social media (Tapia and Moore, 2014).

In social media during emergencies, it is easier to find a message describing something that is true, than it is to find a message describing something that is false (Mendoza et al., 2010).